Drosophila melanogaster lipins are tissue-regulated and developmentally regulated and present specific subcellular distributions

Lipins constitute a novel family of Mg2+-dependent phosphatidate phosphatases that catalyze the dephosphorylation of phosphatidic acid to yield diacylglycerol, an important intermediate in lipid metabolism and cell signaling. Whereas a single lipin is detected in less complex organisms, in mammals there are distinct lipin isoforms and paralogs that are differentially expressed among tissues. Compatible with organism tissue complexity, we show that the single Drosophila Lpin1 ortholog (CG8709, here named DmLpin) expresses at least three isoforms (DmLpinA, DmLpinK and DmLpinJ) in a temporal and spatially regulated manner. The highest levels of lipin in the fat body, where DmLpinA and DmLpinK are expressed, correlate with the highest levels of triacylglycerol (TAG) measured in this tissue. DmLpinK is the most abundant isoform in the central nervous system, where TAG levels are significantly lower than in the fat body. In the testis, where TAG levels are even lower, DmLpinJ is the predominant isoform. Together, these data suggest that DmLpinA might be the isoform that is mainly involved in TAG production, and that DmLpinK and DmLpinJ could perform other cellular functions. In addition, we demonstrate by immunofluorescence that lipins are most strongly labeled in the perinuclear region of the fat body and ventral ganglion cells. In visceral muscles of the larval midgut and adult testis, lipins present a sarcomeric distribution. In the ovary chamber, the lipin signal is concentrated in the internal rim of the ring canal. These specific subcellular localizations of the Drosophila lipins provide the basis for future investigations on putative novel cellular functions of this protein family.

Evaluation of Leptospiral Recombinant Antigens MPL17 and MPL21 for Serological Diagnosis of Leptospirosis by Enzyme-Linked Immunosorbent Assays

Leptospirosis is a zoonosis of multisystem involvement caused by pathogenic strains of the genus Leptospira. In the last few years, intensive studies aimed at the development of a vaccine have provided important knowledge about the nature of the immunological mechanisms of the host. The purpose of this study was to analyze the immune responses to two recombinant proteins, MPL17 and MPL21 (encoded by the genes LIC10765 and LIC13131, respectively) of Leptospira interrogans serovar Copenhageni in individuals during infection. The recombinant proteins were expressed in Escherichia coli as six-His tag fusion proteins and were purified from the soluble bacterial fraction by affinity chromatography with Ni2+ -charged resin. The recombinant proteins were used to evaluate their ability to bind to immunoglobulin G (IgG) (and IgG subclass) or IgM antibodies in serum samples from patients in the early and convalescent phases of leptospirosis (n = 52) by enzyme-linked immunosorbent assays. The prevalences of total IgG antibodies against MPL17 and MPL21 were 38.5% and 21.2%, respectively. The titers achieved with MPL17 were statistically significantly higher than those obtained by the reference microscopic agglutination test. The specificity of the assay was estimated to be 95.5% for MPL17 and 80.6% for MPL21 when serum samples from individuals with unrelated febrile diseases and control healthy donors were tested. The proteins are conserved among Leptospira strains that cause human and animal diseases. MPL17 and MPL21 are most likely new surface proteins of leptospires, as revealed by liquid-phase immunofluorescence assays with living organisms. Our results demonstrate that these recombinant proteins are highly immunogenic and, when they are used together, might be useful as a means of diagnosing leptospirosis.

Radiopacity of Portland Cement Associated With Different Radiopacifying Agents

This study evaluated the radiopacity of Portland cement associated with the following radiopacifying agents: bismuth oxide, zinc oxide, lead oxide, bismuth subnitrate, bismuth carbonate, barium sulfate, iodoform, calcium tungstate, and zirconium oxide. A ratio of 20% radiopacifier and 80% white Portland cement by weight was used for analysis. Pure Portland cement and dentin served as controls. Cement/radiopacifier and dentin disc-shaped specimens were fabricated, and radiopacity testing was performed according to the ISO 6876/2001 standard for dental root sealing materials. Using Insight occlusal films, the specimens were radiographed near to a graduated aluminum stepwedge varying from 2 to 16 mm in thickness. The radiographs were digitized and radiopacity compared with the aluminum stepwedge using Digora software (Orion Corporation Soredex, Helsinki, Finland). The radiographic density data were converted into mmAl and analyzed statistically by analysis of variance and Tukey-Kramer test (alpha = 0.05). The radiopacity of pure Portland cement was significantly lower (p < 0.05) than that of dentin, whereas all cement/radiopacifier mixtures were significantly more radiopaque than dentin and Portland cement alone (p < 0.05). Portland cement/bismuth oxide and Portland cement/lead oxide presented the highest radiopacity values and differed significantly from the other materials (p < 0.05), whereas Portland cement/zinc oxide presented the lowest radiopacity values of all mixtures (p < 0.05). All tested substances presented higher radiopacity than that of dentin and may potentially be added to the Portland cement as radiopacifying agents. However, the possible interference of the radiopacifiers with the setting chemistry, biocompatibility, and physical properties of the Portland cement should be further investigated before any clinical recommendation can be done. (J Endod 2009,35:737-740)

Influence of Filling Materials on the Bonding Interface of Thin-walled Roots Reinforced with Resin and Quartz Fiber Posts

Introduction: A common complication during the restoration of severely destroyed teeth is the loss of coronal root dentine. The aim of this study was to evaluate the influence of different sealers on the bonding interface of weakened roots reinforced with resin and fiber posts. Methods: Sixty extracted maxillary canines were used. The crowns were removed, and the thickness of root dentine was reduced in the experimental (n = 40) and positive control (n = 10) groups. The specimens of experimental group were assigned to four subgroups (n = 10) according to the filling material: gutta-percha + Grossmann`s sealer, gutta-percha + AH Plus (Dentsply De Trey Gmbh, Konstanz, Germany), gutta-percha + Epiphany (Pentron Clinical Technologies, Wallingford, CT), and Resilon (Resilon Research LLC, Madison, CT) + Epiphany. In the negative control group (n = 10), canals were not filled. After post space preparation, the roots were restored with composite resin light-activated through a translucent fiber post. After 24 hours, specimens were transversally sectioned into 1-mm-thick slices. Push-out test and scanning electron microscopic (SEM) analyses of different regions were performed. Data from push-out test were analyzed by using Tukey post hoc multiple comparison tests. The percentage of failure type was calculated. Data from SEM analysis were compared by Friedman and Kruskal-Wallis tests (alpha = 0.05). Results: The mean bond strength was significantly higher in the negative control group as compared with the other groups (P < .05). In all groups, the most frequent type of failure was adhesive. Overall, apical and middle regions presented a lower density of resin tags than the coronal region (P < .05). Conclusions: The push-out bond strength was not affected by sealer or region. The canal region affected significantly the resin tag morphology and density at the bonding interface. (J Endod 2011;37:531-537)